A Hippopotamus opens its mouth wide, and shows off its teeth at the Auckland Zoo in Auckland, on the North Island of New Zealand, a wide open mouth is typical behavior which signals that the animal feels threatened in some way.

Feel free to use this picture as a computer background picture for your desktop screen (aka free wallpaper) - please be aware that this is ONLY allowed for private use!

Windows: right click on the background photo - select "use as background"
Mac: Save the wallpaper to desktop, then in System Preferences (Desktop & Screen Saver) select the background picture as "background"